This invention relates to carburetors and more particularly to a mechanism for moving the carburetor's choke from a first choke break position to a second choke break position faster than would normally occur in response to engine warmup.
Normal carburetor choke operation is such that when an engine on which a carburetor is installed is started, the engine vacuum pulls the choke open to a choke break position and as the engine heats up, the choke is continually moved to a more fully open position. This serves to gradually lean out the air-fuel ratio of the combustible mixture produced by the carburetor. It has been found, however, that this gradual opening of the choke is not satisfactory under certain conditions as, for example, when the engine is accelerated to a cruise condition soon after starting. In such an event, the resultant air-fuel mixture produced by the carburetor is too rich. On the other hand, if a carburetor choke valve is moved too far during its initial opening movement, the air-fuel mixture produced is too lean and the engine will misfire or die. Either of the above circumstances has the disadvantage of greatly increasing the emissions produced by the engine and may result in the engine not meeting federal emission standards.